Use of polysiloxane polyoxyalkylene block copolymers for the preparation of rigid polyurethane foams

ABSTRACT

A process of preparing rigid polyurethane foams is disclosed, wherein polysiloxane polyoxyalkylene block copolymers which have at least one aminofunctional group of the general formula, ##STR1## which is linked to a silicon atom, are used in an amount of 0.2 to 5% by weight, based on the polyol or the prepolymer having isocyanate groups, to provide polyurethane foams, which otherwise contain closed cells, with at least partially open the cells.

BACKGROUND OF INVENTION

This invention relates to the preparation of rigid polyurethane foam andmore particularly to the preparation of rigid polyurethane foam in thepresence of aminofunctional polysiloxane polyoxyalkylene blockcopolymers to obtain rigid foam with at least partially open cells.

According to the state of the art, rigid polyurethane foams are preparedfrom polyols with at least three hydroxyl groups per molecule, at leastdifunctional polyisocyanates, catalysts, blowing agents and polysiloxanepolyoxyalkylene block copolymers as foam stabilizers, as well as, ifnecessary, conventional additives.

A comprehensive account of the raw materials and the methods, which canbe used, is to be found in Ullmann "Enzyklopaedie der technischenChemie" (Encyclopedia of Industrial Chemistry), 1980, volume 19, pages301 to 341 and in the Kunststoff-Handbuch (Plastics Handbook), volumeVII, Polyurethanes, by R. Vieweg and A. Hoechtlen, published by CarlHanser, Munich, 1966, pages 504 to 544.

In general, polyetherols or polyesterols with at least three hydroxylgroups per molecule are used, the OH number of the polyols generallylying between 300 and 800.

As blowing agent, preferably trichlorofluoromethane or a mixture oftrichlorofluoromethane and difluorodichloromethane is used, in generalin combination with water. The water reacts with the isocyanate, carbondioxide and polyurea being split off. The resulting molded articles arealmost always closed cell. The density of the rigid foam is betweenabout 23 and 1,000 (g/L or kg/m³).

If a rigid foam is prepared with a density of less than 23 (g/L), thereis generally shrinkage, that is, the framework of the closed cells canno longer withstand the external air pressure. This shrinkage issupported by the diffusion of the carbon dioxide through the intact cellmembranes in the direction of the surface of the foamed object.

If dimensionally stable, very light, rigid polyurethane foams are to beprepared, excessive amounts of water, for which no corresponding amountof isocyanate is available, are used pursuant to the state of the art.On reaching the boiling range, the excess water evaporates and tears thecell membranes, unless the latter are excessively stabilized.

The so-called I-K foams are a different type of rigid polyurethanefoams. The necessary polyol with the catalysts, the stabilizers and thephysical blowing agent and an appreciable excess of isocyanate is addedhere to a spray can and the mixture is allowed to react in the spraycan. A prepolymer containing isocyanate groups is formed. If the sprayvalve is activated, the blowing agent forces the prepolymer out of thecan and there is spontaneous foaming. A very soft foam is formed atfirst. The isocyanate groups still present react with the moisture ofthe air, forming a largely closed cell, rigid foam. These types of foamare used, for example, for fastening door frames and window frames. Thecavity between the wall and the object that is to be built in is thusformed. Because of fluctuations in air pressure, the closed cell foamexpands or contracts; this has a disadvantageous effect on door andwindow frames, that is, the accuracy of fit of the doors and windowsvaries.

It has been ascertained that the quality and properties of the rigidfoams formed depend in a large measure on the structure and chemicalcomposition of the foam stabilizers used. For this reason, polysiloxanepolyoxyalkylene block copolymers of different structure and differentcomposition have already been described as foam stabilizers.

As polysiloxane polyoxyalkylene block copolymers for the aforementionedpurpose, the German Auslegeschrift 17 19 238, for example, disclosessiloxane oxyalkylene copolymers of the general formula ##STR2## (1=3 to25; x=1 to 25; y=0 to 15; z=2 or 3; p=1 to 10; R=hydrogen or methyl),which are hydrolytically stable, with the proviso that at least 25% byweight of the oxyalkylene groups are oxyethylene groups and, in theevent that R=H, the hydroxyl groups constitute at least 1.5% by weightof the copolymer.

For the preparation of polyurethane foams, the German Patent 20 29 293discloses the use of siloxane-modified carbamic acid derivatives as foamstabilizers, which consist of at least one structural unit of thegeneral formula ##STR3## and further structural units of the generalformula

    R.sub.2 'SiO.sub.2/2

which are linked through Si--O--Si bonds with the first-mentionedstructural unit, at least one structural unit per thousand correspondingto the first-mentioned formula, wherein

R' represents an optionally halogenated or cyano-substituted C₁ -C₁₀alkyl, C₄ -C₁₀ cycloalkyl or C₆ -C₁₀ aryl group,

R" represents a hydrogen atom or a methyl or phenyl group,

R'" represents a C₁ -C₁₀ alkyl, C₄ -C₁₀ cycloalkyl, C₂ -C₁₀ alkenyl, C₇-C₁₀ aralkyl, di(C-C₁₀ alkyl)amino-C₁ -C₁₀ -alkyl, C₆ -C₁₀ aryl, or C₇-C₁₀ alkaryl group,

Q represents a saturated C₁ -C₆ alkyl group or a C₆ aryl group,

m is 1 or 2

n is 2, 3 or 4 and

b is a whole number from 1 to 200

the groups and numerical values at each site of a molecule beingindependent of one another.

Further, particularly suitable polysiloxane polyoxyalkylene blockcopolymers are disclosed in the German Patent 16 94 366. The patentclaims a method for the preparation of polyurethane foams which ischaracterized that polyoxyalkylene polysiloxane block copolymers areused, the polysiloxane block of which, however, is built up in a knownmanner and the polyoxyalkylene block of which consists of 25 to 70% byweight of a polyoxyalkylene with an average molecular weight of 1,600 to4,000 and an ethylene oxide content of 20 to 100% by weight, theremainder being propylene oxide and optionally higher alkylene oxides,and 30 to 75% by weight of a polyoxyalkylene with an average molecularweight of 400 to 1,200 and an ethylene oxide content of 65 to 100% byweight, the remainder being propylene oxide and optionally higheralkylene oxides. The essence of this patent thus is that polyoxyalkyleneblocks of defined, different construction and, with that, of differenthydrophilicity, are contained in the block copolymer.

OBJECTS OF THE INVENTION

It is an object of the invention to provide foam stabilizers, whichensure a stabilization of the cells of rigid polyurethane foams rangingin density from 15 to 100 (g/L) and, at the end of the rising process,bring about at least partial opening of the cells.

Another object of the invention is to assure the formation ofdimensionally stable foams by means of cell openings.

A further object of the invention is to provide a method of preparingrigid polyurethane foam wherein at least part of cells normally closedare open and the dimensional stability of the foam is assured. Itsuffices if an appreciable portion of the cells is opened; it is notnecessary that 100% of the cells be opened.

These and other objects of the invention are accomplished by theinvention disclosed below.

SUMMARY OF THE INVENTION

It has been discovered, according to the invention, that at leastpartial opening of the cells of rigid polyurethane foam, which otherwisecontains closed cells, is achieved by using for the preparation of therigid polyurethane foam polysiloxane polyoxyalkylene block copolymerswhich have at least one aminofunctional group of the general formula##STR4## which is linked to a silicon atom and wherein R⁴ is a divalentgroup,

R⁵ is a hydrogen group or an alkyl group with 1 to 4 carbon atoms, apolyether group of the formula --(C_(q) H_(2q) O)_(r) R⁹ (q=2, 3 or 4,r=1 to 100, R⁹ =a hydrogen group or an alkyl group with 1 to 4 carbonatoms) or the group ##STR5## wherein R⁶ is a divalent aliphatichydrocarbon group with 2 to 6 carbon atoms or a divalent aromatichydrocarbon group,

R⁷ and R⁸ are each an alkyl group with 1 to 4 carbon atoms, which mayhave an OH group or be a common constituent of a 5- or 6-membered ring,which may contain an oxygen or nitrogen atom,

z=0 or 1.

DESCRIPTION OF THE INVENTION

The polysiloxane polyoxyalkylene block copolymer, according to theinvention is used in an amount of about 0.2 to 5% by weight, based onthe weight if the polyol or prepolymer having isocyanate groups. Also,the aminofunctional group of the polysiloxane polyoxyalkylene blockcopolymer can be linked to the polysiloxane backbone over an SiOC or anSiC bond, depending on whether the subscript z has a value of 0 or 1.

R⁴ is a divalent group, particularly a divalent aliphatic hydrocarbongroup with 2 to 6 carbon atoms. Preferably, the R⁴ group is the ##STR6##group, with the proviso that the subscript z is equal to 0 in theaminofunctional group.

R⁵ is a hydrogen group or an alkyl group with 1 to 4 carbon atoms. Asalkyl group, the methyl group is preferred.

R⁵ can also represent a polyether group of the formula --(C_(q) H_(2q)O)_(r) R⁹. In this formula, q has an absolute value of 2, 3 or 4. Theaverage value in the polymeric molecule may be a fractional number from2 to 4. r has a value from 1 to 100. R⁹ is a hydrogen group or an alkylgroup with 1 to 4 carbon atoms, the methyl group once again beingpreferred as alkyl group. The composition of the polyether grouppreferably corresponds to that of the polyoxyalkylene block or blocks ofthe polysiloxane polyoxyalkylene block copolymer, to the siloxane blockof which the amino-functional group is linked.

Finally, R⁵ can also be a group of the formula ##STR7##

R⁶ is a divalent, aliphatic hydrocarbon group with 2 to 6 carbon atoms,preferably a divalent aliphatic hydrocarbon group with 2 to 4 carbonatoms or a divalent aromatic hydrocarbon group, preferably the phenylenegroup.

R⁷ and R⁸ are the same or different and represent alkyl groups with 1 to4 carbon atoms, preferably methyl groups. The alkyl groups can havehydroxyl groups. R⁷ and R⁸ can additionally be a common constituent of a5- or 6-membered ring, which can have an oxygen or a nitrogen atom, suchas ##STR8##

The aminofunctional groups of the polysiloxane polyoxyalkylene blockcopolymers, which are to be used pursuant to the invention, thus have atleast one tertiary and one secondary nitrogen atom or two tertiarynitrogen atoms. This is evidently the structural prerequisite for theability to open at least partially the cells of rigid polyurethanefoams, which otherwise would be closed.

The aminofunctional groups can be a component of a linear or a branchedpolysiloxane polyoxyalkylene block copolymer. If the block copolymer isone with a linear siloxane chain, the aminofunctional groups can belateral and/or terminal.

A preferred embodiment of the object of the present invention thereforeis the use of polysiloxane polyoxyalkylene block copolymers with thegeneral, average formula ##STR9## wherein R¹ is an alkyl group with 1 to6 carbon atoms, but at least 90% of the R¹ groups are methyl groups,

X is a polyoxyalkylene block of the general formula

    --R.sub.p.sup.2 --O--(C.sub.m H.sub.2m O--).sub.m R.sup.3,

in which R² is a divalent alkylene group with 3 to 11 carbon atoms,

R³ is a hydrogen group or an alkyl group with 1 to 4 carbon atoms,

p has a value of 0 or 1,

m represents the number 2, 3 or 4, the average value of which is 2.0 to2.7,

n has a value of 1 to 100,

Y is an aminofunctional group of the formula ##STR10## in which R⁴, R⁵,R⁶, R⁷, R⁸ and z have the meaning already given,

Z represents X, Y or R¹,

a has a value of 10 to 150,

b has a value of 1 to 20,

c has a value of 1 to 20.

In formula, I, R¹ is an alkyl group with 1 to 6 carbon atoms. At least90% of the R¹ groups are methyl groups. Preferably however, all the R¹are methyl groups.

X is a polyoxyalkylene block of the general formula

    --R.sub.p.sup.2 --O--(C.sub.m H.sub.2m O--).sub.n R.sup.3

In this formula of the polyoxyalkylene block, R² is a divalent alkylenegroup with 3 to 11 carbon atoms, particularly the --(CH₂)₃ -- or--(CH₂)₁₁ -- group. The --(CH₂)₃ -- group is especially preferred.

R³ is a hydrogen group of an alkyl group with 1 to 4 carbon atoms,particularly a methyl group. p has a value of 0 or 1 and m an absolutevalue of 2.3 or 4. However the average value of m in the polymericmolecule is 2.0 to 2.7.

n has a value of 1 to 100.

Y once again is an aminofunctional group of the already describedformulas ##STR11##

In these formulas, the R⁴, R⁵, R⁶, R⁷, R⁸ groups and the subscript zhave the meaning already given.

Z represents X, Y or R¹.

a has a value of 10 to 150 and preferably of 15 to 90.

b has a value of 1 to 20 and preferably of 1 to 10.

c has a value of 1 to 20 and preferably of 1 to 10.

The ratio of the subscripts b:c preferably is 0.9:0.1 to 0.2:0.8.

The aminofunctional groups can also be a constituent of a branchedpolysiloxane polyoxyalkylene block copolymer.

A further preferred embodiment of the object of the present inventiontherefore consists of the use of polysiloxane polyoxyalkylene blockcopolymers with the general average formula ##STR12##

In this formula II, R¹ has the meaning already given. R¹⁰ is selectedfrom the group comprising R¹, X and Y, which have already been describedin detail above. However the condition, that there is at least one Xgroup and at least one Y group in the average molecule, must befulfilled.

d has a value of 0 to 20 and preferably a value of 1 to 10.

e has a value of 0 to 20 and preferably a value of 1 to 10.

f has a value of 1 to 10 and preferably a value of 1 to 6.

g has a value of 0 to 20 and preferably a value of 1 to 10.

Independently of the structure of the framework of the polysiloxanepolyoxyalkylene block copolymer, aminofunctional groups are preferred,in which R⁵ is a hydrogen group or a methyl group, R⁶ is a --(CH₂)₃ --group and R⁷ and R⁸ in each case represent a methyl group.

The compounds, which are to be used pursuant to the invention, arepreferably added to the polyol component or to the prepolymer that hasthe isocyanate groups in an amount of 0.2 to 5% by weight and preferablyin an amount of 0.5 to 2% by weight.

The compounds, which are to be used pursuant to the invention, can beprepared by methods known in the art. In a preferred method, anorganopolysiloxane, which has SiH groups, is reacted with a mixture ofan allyl polyether and an allyl glycidyl ether in the presence of ahydrosilylation catalyst. After removal of excess allyl glycidyl ether,the product is reacted with N,N-dialkylaminoalkylamine.

In a different method, a polyoxyalkylene ether monool is first mixedwith N,N-dialkylaminoalkylmethylaminoalkanol and the mixture is reactedwith a chloropolysiloxanyl sulfate, as disclosed in U.S. Pat. No.3,115,512.

In the method named first, modified organopolysiloxanes are obtained, towhich polyether blocks and amines are linked over SiC bonds. In thesecond case, similar compounds with SiOC bonds are formed. Those skilledin the art can infer further details of this method from Examples 1 to10.

Examples of compounds, which are to be used pursuant to the inventionare: ##STR13##

In the following Examples, the preparation of the inventive compounds isdescribed first. In further examples, the opening of the cells, broughtabout by the use of these compounds, is proven.

EXAMPLE 1

To a flask, equipped with dropping funnel, stirrer, thermometer, gasinlet and reflux condenser, 135 g (0.125 moles) of a polyether havingthe average formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.14 (OC.sub.3 H.sub.6).sub.7 OH

14.3 g (0.125 moles) of allyl glycidyl ether and 4 mg of cis-[PtCl₂(NH₃)₂ ] are added. Nitrogen is passed through the apparatus. At atemperature of 110° to 115° C., 74.6 g (0.2 moles SiH) of a siloxane ofthe average formula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.40 [(CH.sub.3)HSiO].sub.10 Si(CH.sub.3).sub.3

are added dropwise over a period of 25 minutes. Subsequently, thereaction is continued for 2 hours. After that, the excess allyl glycidylether is distilled off under vacuum (20 mbar). For this, the temperatureof the contents of the flask is increased to 140° C. At the end, theproduct is mixed at 80° C. with 2 g of bentonite, stirred for 30 minutesand filtered. A clear product, colored yellowish, is obtained. The SiHconversion is 99.2% (determined by the hydrogen, which can be split offwith n-butanol in an alkaline medium). The content of epoxy oxygen is0.76% (theoretical content=0.72).

To a flask equipped with stirrer, thermometer and reflux condenser, 190g (=0.09 moles of epoxy groups) of the polyethersiloxane, which isobtained and contains epoxy groups, and 13.8 g (=0.135 moles) ofN,N-dimethylaminopropylamine are added, heated to 80° C. and stirred for5 hours. After that, the excess amine is distilled off at 140° C. and 20mbar. A clear, yellow-brown product, with a nitrogen content of 1.2%(theoretical content: 1.27%) and a viscosity at 25° C. of 1106 mPas,remains behind.

EXAMPLE 2

To a flask equipped with dropping funnel, stirrer, thermometer, gasinlet and reflux condenser, 189 g (=0.175 moles) of a polyether ofaverage formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.14 (OC.sub.3 H.sub.6).sub.7 OH

8.6 g (=0.075 moles) of allyl glycidyl ether and 4 mg of cis-[PtCl₂(NH₃)₂ ] are added. Nitrogen is passed through the apparatus. At atemperature of 110° to 115° C., 74.6 g (=0.2 moles SiH) of a siloxane ofaverage formula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.40 [(CH.sub.3)HSiO].sub.10 Si(CH.sub.3).sub.3

are added dropwise within 20 minutes. The reaction is subsequentlyallowed to continue for 2 hours. After that, the excess allyl glycidylether is distilled off at 20 mbar. In so doing, the temperature of thecontents of the flask is increased to 140° C. A small sample is takenfrom the batch for analysis. The conversion of SiH is 98.5% and theepoxy oxygen content is 0.33% (theoretical content: 0.35%). The batch istreated at room temperature with 12.3 g (=0.12 moles) ofN,N-dimethylaminopropylamine, heated and stirred for 5 hours at 80° C.After that, the excess amine is distilled off at 140° C. and 20 mbar. Aclear, yellow-brown product with a nitrogen content of 0.55%(theoretical content: 0.61%) and a viscosity at 25° C. of 874 mPas isobtained.

EXAMPLE 3

Under the conditions of Example 1, 153.2 g (=0.125 moles) of a polyetherof the average formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.17 (OC.sub.3 H.sub.6).sub.7 OCH.sub.3

and 14.3 g (=0.125 moles) of allyl glycidyl ether are reacted with 74.6g (=0.2 moles SiH) of a siloxane of the average formula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.40 [(CH.sub.3)HSiO].sub.10 Si(CH.sub.3).sub.3

in the presence of 8 mg of cis-[PtCl₂ (NH₃)₂ ] and worked up. Theintermediate is clear and yellow-brown. The SiH conversion is 97.4% andthe epoxy oxygen content is 0.07% (theoretical content: 0.67%).

As in Example 1, 183 g (=0.08 moles epoxy groups) of the intermediate,which contains epoxy groups, is reacted with 16.4 g (=0.16 moles) ofN,N-dimethylaminopropylamine. A clear, yellow-brown product, with anitrogen content of 1.03% (theoretical content: 1.17%) and a viscosityat 25° C. of 614 mPas, is obtained.

EXAMPLE 4

Under the conditions of Example 1, 135 g (=0.125 moles) of a polyetherof the average formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.14 (OC.sub.3 H.sub.6).sub.7 OH

and 14.3 g (=0.125 moles) of allyl glycidyl ether are reacted with 68.7g (=0.2 moles SiH) of a siloxane of average formula

    H(CH.sub.3).sub.2 SiO[(CH.sub.3).sub.2 SiO].sub.38 [(CH.sub.3)HSiO].sub.8 Si(CH.sub.3).sub.2 H

in the presence of 3 mg of cis-[PtCl₂ (NH₃)₂ ] and worked up. Theintermediate is clear and yellow. The SiH conversion is 99% and theepoxy oxygen content is 0.07% (theoretical content: 0.74%).

As in Example 1, 171 g (=0.075 moles of epoxy groups) of theintermediate, which contains epoxy groups, is reacted with 15.3 g (=0.15moles) of N,N-dimethylaminopropylamine. A clear, yellow-brown product isobtained with a nitrogen content of 1.05% (theoretical content: 1.17%)and a viscosity at 25° C. of 980 mPas.

EXAMPLE 5

Under the conditions of Example 2, 95 g (0.125 moles) of a polyether ofthe average formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.12 (OC.sub.3 H.sub.6).sub.3 OH

and 14.3 g (=0.125 moles) of allyl glycidyl ether are reacted with 83.8g (=0.2 moles) of a siloxane of average formula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.22 [(CH.sub.3)HSiO].sub.5 Si(CH.sub.3).sub.3

in the presence of 3 mg of cis-[PtCl₂ (NH₃)₂ ]. Analysis reveals an SiHconversion of 98.3% and an epoxy oxygen content of 0.82% (theoreticalcontent: 0.84%).

The intermediate, without being worked up, is reacted as in Example 2with 20.4 g (=0.2 moles) of N,N-dimethylaminopropylamine. A clearyellow-brown product with a nitrogen content of 1.32% (theoreticalcontent: 1.40%) and a viscosity at 25° C. of 750 mPas is obtained.

EXAMPLE 6

Under the conditions of Example 1, 108.4 g (=0.108 moles) of a polyetherof average formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.15 (OC.sub.3 H.sub.6).sub.5 OH

and 16.3 g (=0.143 moles) of allyl glycidyl ether are reacted with 76 g(=0.2 moles SiH) of a siloxane of the average formula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.28 [(CH.sub.3)HSiO].sub.7 Si(CH.sub.3).sub.3

in the presence of 5 mg of cis-[PtCl₂ (NH₃)₂ ] and worked up. Theintermediate is clear and yellow-brown. The product contains 0.87% epoxyoxygen (theoretical content: 0.92%) and the SiH conversion is 98.3%.

As in Example 1, 147 g (=0.08 moles epoxy groups) of the intermediate,which contains epoxy groups, is reacted with 20 g (=0.2 moles) ofN-methylpiperazine. A clear, yellow-brown product is obtained, which hasa nitrogen content of 1.5% (theoretical content: 1.44%) and a viscosityat 25° C. of 547 mPas.

EXAMPLE 7

To a flask, equipped with stirrer, thermometer, gas inlet anddistillation head, 101.4 g (=0.11 moles) of a polyether of averageformula

    C.sub.4 H.sub.9 --(OC.sub.2 H.sub.4).sub.14 (OC.sub.3 H.sub.6).sub.4 OH

200.6 g (=0.11 moles) of a polyether of average formula

    C.sub.4 H.sub.9 --(OC.sub.2 H.sub.4).sub.20 (OC.sub.3 H.sub.6).sub.15 OH

and 850 mL of toluene are added. Under a blanket of nitrogen 150 mL oftoluene are distilled off in order to dry the polyether mixtureazeotropically. At 50° C., the distillation head is exchanged for areflux condenser. Subsequently, 38.4 g (=0.22 moles) of the compound##STR14## are added to the flask first and mixed in well and then 174 g(=0.1 moles) of a siloxane of average formula ##STR15## in which 75% ofterminal group a consists of Cl and 25% of SO_(4/2). After the siloxanehas been mixed in well (10 minutes), ammonia gas is passed in at 50° C.until the contents of the flask react ammoniacally. The reaction isallowed to proceed for a further hour with continued introduction ofammonia gas. The precipitated salt is subsequently filtered off. Afterthat, toluene is distilled off at 70° C. and 20 mbar. A light-brown,almost clear product is obtained. Its viscosity at 25° C. is 1015 mPasand the nitrogen content is 1.15% (theoretical content: 1.23%).

EXAMPLE 8

Under the conditions of Example 1, 405 g (=0.375 moles) of a polyetherof average formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.14 (OC.sub.3 H.sub.6).sub.7 OH

and 42.8 g (=0.375 moles) of allyl glycidyl ether are reacted with 223.8g (=0.6 moles SiH) of a siloxane of the average formula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.40 [(CH.sub.3)HSiO].sub.10 Si(CH.sub.3).sub.3

in the presence of 15 mg of cis-[PtCl₂ (NH₃)₂ ] and worked up. Theintermediate is clear and yellow brown. The SiH conversion is 99.4% andthe epoxy oxygen content 0.69% (theoretical content: 0.72%).

As in Example 1, 185 g (=0.08 moles epoxy groups) of the intermediate,which contains epoxy groups, are reacted with 28.8 g (=0.02 moles) of3-morpholinopropylamine. A clear, yellow-brown product with a nitrogencontent of 1.08% (theoretical content: 1.14%) and a viscosity at 25° C.of 1050 mPas is obtained.

EXAMPLE 9

As in Example 1, 185 g (=0.08 moles epoxy groups) of the intermediate,obtained in Example 8 and containing epoxy groups, is reacted with 26.0g (=0.2 moles) of 2-piperazinoethanol. After the reaction, the excessamine is distilled off at 120° C. and 1 mbar. A clear, light-yellowproduct, which contains 1.24% nitrogen (theoretical content: 1.15%) andhas a viscosity of 980 mPas at 25° C., is obtained.

EXAMPLE 10

As in Example 1, 185 g (=0.08 moles epoxy groups) of the intermediate,which is obtained in Example 8 and contains epoxy groups, is reactedwith 27.2 g (=0.2 moles) of N,N-dimethyl-1,4-phenylenediamine. After thereaction, the excess amine is distilled off at 120° C. and 1 mbar. Aclear, light-brown product, which contains 1.20% nitrogen (theoreticalcontent: 1.14%) and has a viscosity of 1,278 mPas at 25° C., isobtained.

EXAMPLE 11 (not of the invention)

The siloxane, used in Example 1, is reacted only with the polyether usedin Example 1.

To an apparatus, as described in Example 1, 135 g (=0.125 moles) of apolyether of average formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.14 (OC.sub.3 H.sub.6).sub.7 OH

and 37.3 g (=0.1 moles SiH) of a siloxane of average formula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.40 [(CH.sub.3)HSiO].sub.10 Si(CH.sub.3).sub.3

are reacted in the presence of 4 mg of cis-[PtCl₂ (NH₃)₂ ]. For this,the polyether and the platinum compound are added under a blanket ofnitrogen at 110° to 115° C. and the siloxane is added dropwise within 20minutes. The reaction is allowed to continue for a further 3 hours,after which the batch is reacted as in Example 1 with 1.5 g of bentoniteand filtered. The SiH conversion is 98.7% and the viscosity at 25° C. is1105 mPas.

EXAMPLE 12 (not of the invention)

The comparison is carried out similar to Example 1. However, instead ofthe allyl glycidyl ether, the compound

    CH.sub.2 ═CH--CH.sub.2 --O--CH.sub.2 CHOH--CH.sub.2 --OCH.sub.3

is used. A copolymer is thus obtained, which does not contain theinventive amino groups, but otherwise has a similar structure.

As described in Example 1, 135 g (=0.125 moles) of a polyether of theaverage formula

    CH.sub.2 ═CH--CH.sub.2 --(OC.sub.2 H.sub.4).sub.14 (OC.sub.3 H.sub.6).sub.7 OH

and 18.3 g (=0.125 moles) of allyl 2-hydroxy-3-methoxypropyl ether arereacted with 74.6 g (=0.2 moles SiH) of a siloxane of the averageformula

    (CH.sub.3).sub.3 SiO[(CH.sub.3).sub.2 SiO].sub.40 [(CH.sub.3)HSiO].sub.10 Si(CH.sub.3).sub.3

in the presence of 7 mg of cis-[PtCl₂ (NH₃)₂ ]. After the post-reaction,volatile components are distilled off at 140° C. and 20 mbar. Theresidue in treated with 2.5 g of bentonite and filtered. The SiHconversion is 96.9% and the viscosity at 25° C. is 1047 mPas. PG,31

I. Application Testing of the Stabilization and Cell Opening ofStabilizers, Which are to be Used Pursuant to the Invention in RigidPolyurethane Foams

A rigid polyurethane foam is prepared according to the state of the art,in the following manner:

Formulation A)

100 g rigid foam polyol, for example, with an OH number of 500

1.0 g water

3.0 g triethylamine

1.0 g stabilizer and

40.0 g trichlorofluoromethane

are stirred for 50 sec. at 1,000 rpm for the purpose of homogenization.The air, which is beaten in at the same time, serves as a nucleationaid, in order to arrive at a fine celled foam.

After that, 155 g of a crude diphenylmethane diisocyanate (MDI),corresponding to an index of 110, are added to this mixture. The mixtureis then stirred intensively for 7 seconds at 2,500 rpm. The homogenizedmixture is then added to a paper-lined mold. The foam that is formedrises in about 2 minutes and consolidates. After 24 hours, the foam iscut open and investigated with the help of the Beckmann "Air ComparisonPycnometer Model 930" for the percentage of open cells.

Formulation B)

100 g rigid foam polyol, for example, with an OH number of 550

4.0 g water

1.5 g dimethylcyclohexylamine

1.0 g stabilizer and

212 g crude MDI with an index of 110

are treated as under A) and foamed. The percentage of open cells isdetermined as in A).

Foamings with Stabilizers Prepared in Examples 1 to 12

    ______________________________________                                        Stabilizer                                                                            Of The     Formulation A)                                                                            Formulation B)                                 of Example                                                                            Invention  % Open Cells                                                                              % Open Cells                                   ______________________________________                                        1       yes        >95         >95                                            2       yes        78          87                                             3       yes        >95         >95                                            4       yes        93          >95                                            5       yes        92          >95                                            6       yes        18          24                                             7       yes        15          20                                             8       yes        21          26                                             9       yes        22          25                                             10      yes        18          24                                             11      no         <5          <5                                             12      no         <5          <5                                             ______________________________________                                    

Formulation C)

100 g rigid foam polyol with an OH number of 500,

1.0 g water,

3.0 g triethylamine,

1.0 g stabilizer

20 g trifluoromethane and

155 g crude MDI with an index of 110.

The use of stabilizers of Example 1 leads to more than 95% open cells.

Formulation D)

100 g rigid foam polyol with an OH number of 500,

1.0 g water,

3.0 g triethylamine,

1.0 g stabilizer,

10 g trifluoromethane and

155 g crude MDI with an index of 110

In this formulation, the stabilizer of Example 1 produces 75% opencells.

I. Application Testing of the Dimensional Behavior of PolyurethaneFoams, Which were Obtained with Stabilizers of the Invention and not ofthe Invention

For this test, a 10 cm×10 cm×10 cm foam cube is stored for 24 hours at-30° C. After thawing, the change in volume (shrinkage) is determined.The density of the foams tested is between 22.5 and 24.2. Formulation A)is used; however, 45 g of trifluoromethane are employed.

    ______________________________________                                                                        Dimensional                                   Stabilizer of                                                                          Of The     Concentration                                                                             Stability                                     Example  Invention  Employed (%)                                                                              % Shrinkage                                   ______________________________________                                         1       yes        0.5         <1                                             1       yes        1.0         <1                                             1       yes        1.5         <1                                            11       no         0.5         39                                            11       no         1.0         39                                            11       no         1.5         40                                            ______________________________________                                    

We claim:
 1. A method of producing rigid polyurethane foam, whereinpolyol is reacted with at least difunctional polyisocyanate with the aidof catalyst, blowing agent and foam stabilizer which is a polysiloxanepolyoxyalkylene block copolymer, comprising using for the production ofthe rigid polyurethane a polysiloxane polyoxyalkylene block copolymerwhich has at least one aminofunctional group of the formula ##STR16##which is linked to a silicon atom and wherein R⁴ is a divalent group,R⁵is a hydrogen group or an alkyl group with 1 to 4 carbon atoms, apolyether group of the formula --(C_(q) H_(2q) O)_(r) R⁹, wherein q=2, 3or 4, r=1 to 100, R⁹ is a hydrogen group or an alkyl group with 1 to 4carbon atoms, or the group ##STR17## R⁶ is a divalent aliphatichydrocarbon group with 2 to 6 carbon atoms or a divalent aromatichydrocarbon group, R⁷ and R⁸ are each alkyl groups with 1 to 4 carbonatoms, which may have an OH group or be a common constituent of a 5- or6-membered ring, which may contain an oxygen or nitrogen atom and Z=0 or1whereby the cells of the rigid polyurethane foam, which otherwise areclosed, are at least partially opened.
 2. The method of producing rigidpolyurethane foam according to claim 1 in which the rigid polyurethanefoam is produced using 0.2 to 5% by weight of the polysiloxanepolyoxyalkylene block copolymer based on the weight of polyol or basedon the weight of prepolymer formed during the reaction and containingisocyanate groups.
 3. The method of producing rigid polyurethane foamaccording to claim 2, in which the polysiloxane polyoxyalkylene blockcopolymer has the average formula ##STR18## wherein R¹ is an alkyl groupwith 1 to 6 carbon atoms, but at least 90% of the R¹ groups are methylgroups,X is a polyoxyalkylene block of the formula

    --R.sub.p.sup.2 --O--(C.sub.m H.sub.2m O--).sub.n R.sup.3,

in whichR² is a divalent alkylene group with 3 to 11 carbon atoms, R³ isa hydrogen group or an alkyl group with 1 to 4 carbon atoms, p has avalue of 0 or 1, m represents the number 2, 3 or 4, the average value ofwhich is 2.0 to 2.7 and n has a value of 1 to 100, Y is anaminofunctional group of the formula ##STR19## in which R⁴, R⁵, R⁶, R⁷,R⁸ and z have the meaning already given, Z represents X, Y or R¹, a hasa value of 10 to 150, b has a value of 1 to 20 and c has a value of 1 to20.
 4. The method of producing rigid polyurethane foam according toclaim 3, in which the ratio of b:c in the polysiloxane polyoxyalkyleneblock copolymer is 0.9:0.1 to 0.2:0.8.
 5. The method of producing rigidpolyurethane foam according to claim 2, in which the polysiloxanepolyoxyalkylene block copolymer has the average formula ##STR20##wherein R¹ has the meaning already given,R¹⁰ is selected from the groupcomprising R¹, X and Y, which have the meaning already given, with theproviso that at least one X group and one Y group must be present in theaverage molecule d has a value of 0 to 20, e has a value of 0 to 20, fhas a value of 1 to 10 and g has a value of 0 to
 20. 6. The method ofproducing rigid polyurethane foam according to claim 5, in whichd has avalue of 1 to 10, e has a value of 1 to 10, f has a value of 1 to 6 andg has a value of 1 to
 10. 7. The method of producing rigid polyurethanefoam according to claim 3, in which R¹ is a methyl group.
 8. The methodof producing rigid polyurethane foam according to claim 3, wherein z inthe aminofunctional group of the polysiloxane polyoxyalkylene blockcopolymer has value of 0 and R⁴ is a group having the formula --(CH₂)₃--O--CH₂ --CHOH--CH₂ --.
 9. The method of producing rigid polyurethanefoam according to claim 3, in which in the polysiloxane polyoxyalkyleneblock copolymerR⁵ is a hydrogen atom or a methyl group, R⁶ is a --(CH₂)₃-- group and R⁷ and R⁸ are each a methyl group.
 10. A method of at leastpartially opening the cells of rigid polyurethane foam, wherein thepolyurethane foam is produced by reacting polyol with at leastdifunctional polyisocyanate with the aid of catalyst, blowing agent andfoam stabilizer which is a polysiloxane polyoxyalkylene block copolymer,comprising producing the rigid polyurethane foam with a polysiloxanepolyoxyalkylene block copolymer which has at least one aminofunctionalgroup of the formula ##STR21## which is linked to a silicon atom andwherein R⁴ is a divalent group,R⁵ is a hydrogen group or an alkyl groupwith 1 to 4 carbon atoms, a polyether group of the formula --(C_(q)H_(2q) O)_(r) R⁹, wherein q=2, 3 or 4, r=1 to 100, R⁹ is a hydrogengroup or an alkyl group with 1 to 4 carbon atoms, or the group ##STR22##R⁶ is a divalent aliphatic hydrocarbon group with 2 to 6 carbon atoms ora divalent aromatic hydrocarbon group, R⁷ and R⁸ are each an alkyl groupwith 1 to 4 carbon atoms, which may have an OH group or be a commonconstituent of a 5- or 6-membered ring, which may contain an oxygen ornitrogen atom and z=0 or
 1. 11. The method of at least partially openingthe cells of rigid polyurethane foam according to claim 10, in which therigid polyurethane foam is produced with 0.2 to 5% by weight of thepolysiloxane polyoxyalkylene block copolymer based on the weight ofpolyol or based on the weight of prepolymer formed during the reactionand containing isocyanate groups.
 12. The method of at least partiallyopening the cells of rigid polyurethane foam according to claim 11, inwhich the polysiloxane polyoxyalkylene block copolymer has the averageformula ##STR23## wherein R¹ is an alkyl group with 1 to 6 carbon atoms,but at least 90% of the R¹ groups are methyl groups,X is apolyoxyalkylene block of the formula

    --R.sub.p.sup.2 --O--(C.sub.m H.sub.2m O--).sub.n R.sup.3,

in whichR² is a divalent alkylene group with 3 to 11 carbon atoms, R³ isa hydrogen group or an alkyl group with 1 to 4 carbon atoms, p has avalue of 0 or 1, m represents the number 2, 3 or 4, the average value ofwhich is 2.0 to 2.7 and n has a value of 1 to 100, Y is anaminofunctional group of the formula ##STR24## in which R⁴, R⁵, R⁶, R⁷,R⁸ and z have the meaning already given, Z represents X, Y or R¹, a hasa value of 10 to 150, b has a value of 1 to 20 and c has a value of 1 to20.
 13. The method of at least partially opening the cells of rigidpolyurethane foam according to claim 12, in which the ratio of b:c inthe polysiloxane polyoxyalkylene block copolymer is 0.9:0.1 to 0.2:0.8.14. The method of at least partially opening the cells of rigidpolyurethane foam according to claim 11 in which the polysiloxanepolyoxyalkylene block copolymer has the average formula ##STR25##wherein R¹ has the meaning already given,R¹⁰ is selected from the groupcomprising R¹, X and Y, which have the meaning already given, with theproviso that at least one X group and one Y group must be present in theaverage molecule d has a value of 0 to 20, e has a value of 0 to 20, fhas a value of 1 to 10 and g has a value of 0 to
 20. 15. The method ofat least partially opening the cells of rigid polyurethane foamaccording to claim 14, in whichd has a value of 1 to 10, e has a valueof 1 to 10, f has a value of 1 to 6 and g has a value of 1 to
 10. 16.The method of at least partially opening the cells of rigid polyurethanefoam according to claim 12, in which R¹ is a methyl group.
 17. Themethod of at least partially opening the cells of rigid polyurethanefoam according to claim 12, wherein z in the aminofunctional group ofthe polysiloxane polyoxyalkylene block copolymer has value of 0 and R⁴is a group having the formula --(CH₂)₃ --O--CH₂ --CHOH--CH₂ --.
 18. Themethod of at least partially opening the cells of rigid polyurethanefoam according to claim 12, in which in the polysiloxane polyoxyalkyleneblock copolymerR⁵ is a hydrogen atom or a methyl group, R⁶ is a --(CH₂)₃-- group and R⁷ and R⁸ are each a methyl group.
 19. The method of atleast partially opening the cells of rigid polyurethane foam accordingto claim 12, in which the polysiloxane polyoxyalkylene block copolymeris added to the polyol.
 20. The method of at least partially opening thecells of rigid polyurethane foam according to claim 12, in which thepolyol and the diisocyanate are reacted to form prepolymer havingisocyanate groups and the polysiloxane polyoxyalkylene block copolymeris added to the prepolymer.
 21. The product obtained by the method ofclaim 1.